isSeatingPossible.js

function isZeroArr(arr) {
  if (!arr.length) return false
  for (let i = 0; i < arr.length - 1; i++) {
    if (arr[i] != 0) return false;
  }
  return true;
}

function isPossible(row, folks) {
  var rowLen = row.length
  
  if (!rowLen) return false
  
  if (rowLen < folks) return false

  if (rowLen == 1 && (folks == 1 || folks == 0)) return true
  
  // Boundary 
  if (row[0] == 0) {
    let t = row.slice(0, folks + 2)
    if(isZeroArr(t)) return true
  }
  
  if (row[rowLen - 1] == 0) {
    let s = row.slice(rowLen - folks - 1, rowLen)
    if(isZeroArr(s)) return true
  }

  // Middle
  let expectedEmptySeats = folks + 2;
  let numEmptySeats = 0;
  
  for (let i = 1; i < rowLen - 1; i++) {
    if (row[i] == 0) numEmptySeats++
    if (numEmptySeats >= expectedEmptySeats) return true
    if (row[i] == 1) numEmptySeats = 0
  }

  return false
  
}

var ar1 = [0];
console.log(isPossible(ar1, 0)) // true
console.log(isPossible(ar1, 1)) // true
console.log(isPossible(ar1, 2)) // false
 
// Boundary
var ar2 = [1,0,0,1,0,0,1,0,0];
console.log(isPossible(ar2, 1)) // true
console.log(isPossible(ar2, 2)) // false

// Middle
var arr3 = [1, 0, 0, 0, 0, 0, 1, 0, 0];
console.log(isPossible(arr3, 3)) // true
console.log(isPossible(arr3, 4)) // false